Grinding machine



May 6 1947' H. E. BALSIGER ErAL 2,419,940

GRIHDING MACHINE Filed March 3, 1944 5 Sheets-Shoot l .1. ula? a..

Summer {lazoLn 841.31652 'Jou/v .aLLER Gttorncg May 6 1947. yH. E.BALSIGER Erm. 2,419,940

GRINDING MACHINE Filed March I5, 1944 5 Sheets-Sheet 2 Bnventor #4201.0544.51692 Jou/v 4 .BoLLER JM): MAK

Gttomeg May 61 1947 H. E. BALslGr-:R ETAL 214191940 GRINDING MACHINEFned laren s. 1944 s sheets-sheet 3 May 5, 1947- H. E. BALslGc-:R Erm.2,419,940

GRINDING' MACHINE Filed March v3, 1944 5 Sheets-Sheet 4 May 6 1947 H. E.BALslGl-:R ETAL 2,419,940

GRINDING MACHINE Filed March 3, 1944 5 Sheets-Sheet 5 Snoentor #from Ianus/cre Jo/wv A. Bac l. 5 2

attorney Patented May 6, 1947 GRINDING MACHINE Harold E. Balsiger,Waynesboro, Pa., and John A. Boiler, Thurmont, Md., assignors to LandisTool Company, Waynesboro, Pa.

Application March 3, 1944, Serial No. 524,948

21 Claims.

This invention relates to a grinding machine, particularly of thecenterless type.

It is an object of this invention to provide a machine of the centerlesstype having new and improved features of design.

A further object is to provide a novel means for mounting a controlwheel support for angular adjustment in a vertical plane.

A further object is to provide a simple means for effecting said angularadjustment.

A further object is to provide a control wheel support which may also beangularly adjusted in a horizontal plane and traversed or adjusted inany angular position.

A further object is to provide a dressing tool for the control wheelpermanently mounted on the work rest which is in turn mounted on th'ebed.

A further object is to provide novel means for varying the speed of thecontrol wheel.

A further object is to provide an improved driving means for saidcontrol wheel.

A further object is to provide a simplified control means for alloperating conditions.

In the drawings:

Figure 1 is a front elevation.

, Figure 2 is a plan view partly broken away to show the grinding wheelfeed mechanism.

Figure 3 is an enlarged front elevation of the control wheel supportpartly in section to show adjusting mechanisms.

Figure 4 is'a left end elevation of the control wheel mounting partly insection to show means for tilting andtraversing same.

Figure 5 is a partial plan view showing the positionof the parts duringthe dressing of the con trol wheel.

Figure 6 is a front elevation of the same.

Figure 'I is a wiring diagram.

Fgure 8 is a piping diagram.

Figure 9 is a section on line 9--9 of Figure 10.

Figure 10` is a partial front elevation of the valve knob and latch forthe control wheel traverse movement.

Numeral l indicates the bed of a machine, li a grinding wheel baseslidably mounted thereon for movement toward and from a work piece i2. Agrinding wheel i is rotatably mounted on said base i I. Said grindingwheel may be moved toward and from working position by means of a screw20, rotatably mounted in said wheel support and engaging a nut 2|secured to said bed. Said screw may be rotated by means of hand wheel 25acting thru a differential transmission not shown, a shaft 28 having aworm gear 21 thereon meshing with the teeth of a worm wheel 28 on saidscrew. Shaft 28 may be rotated either by means of hand wheel 25 or by a.handle 29 in ring 3i which may be clamped to hand wheel 25 by means of aclamping bolt 30. The range of movement of handle 29 may be limited byany suitable combination of stop devices. The grindwheel i5 is driven bya motor (not shown) on the wheel base.

Control wheel.-A control wheel 35 is rotatably mounted on a wheel base36 and driven thru a V belt drive by a variable voltage motor 3l mountedon said base 36.

Said V belt drive includes a jackshaft 33 driven by motor 31 thru Vbelts 32. A lubricating pump is driven from said jackshaft. V belts 34connect said jacksh'aft and the spindle 38 on which control wheel 35 ismounted. Under some conditions an adjustable chain belt drive may beused between said jackshaft and said spindle as shown in Figure 3.However such a drive must be kept free from backlash. So long as a partof the drive is resilient and the drive as a whole is free from lostmotion the desired results may be attained.

This structure represents a decided improvement over previous controlwheel drives. Such drives consisted of a geared speed change from whichthe control wheel was driven directly or thru a belt. The favorablecharacteristics of the belt portion of the drive were decidedlyoutweighed by the unfavorable characteristics of the geared speed changemechanism.

For example said control wheel rotates at a predetermined speed. As soonas a work piece is introduced into the grinding throat it is picked upby the grinding wheel which tends to rotate the work at the sainersurface speed as the grinding wheel. The control wheel prevents therotation of said work at such a speed but in so doing its own speed isincreased so that the control wheel is really being partially driven bythe grinding wheel thru the medium of the work. Where there is a gearedspeed change in the control wheel drive, this tendency of the controlwheel to be driven by the rotating work piece is suddenlyl checked whenthe backlash in said speed chage is taken up. This results in damage tothe surface being ground and is directly proportional to the amount ofstock being removed. The ability of the grinding wheel to remove stockis thus limited by the characteristics ofthe control Wheel drive. When adrive consisting only of resilient V belts or one in which a combinationof V belt and backlash-free-chain belt is used, the belt partiallycushions the shock of the change in the control wheel drive from drivingto being driven and transmits to the motor all such changes in speed.Motor 31 is designed for this type of operation and assists in saidcushioning action. When said wheel is thus driven the iiow of current isreversed and resistance to the reverse now acts as a dampening brake onthe motor. This is generally known as regenerative braking. By usingsuch a drive the amount of stock which may be removed without effectingthe ground surface is greatly increased.

Said motor 35 is energized by a variable voltage generator |44 mountedin the bed of the machine and adjusted by means of a rheostat, also inthe bed, the handle of which is identified by numeral 49. This type ofdrive makes possible the slow motor speed required by a control wheelusing only the limited reduction available with a belt transmissioninstead of a geared reduction unit. With only a belt drive between motorand wheel spindle the over running tendency of the Wheel is immediatelytransmitted to the motor and the action cushioned yby the effect of theregenerative braking circuit on the motor. Wheel 35 on base 36 may beadjusted angularly in a horizontal plane for grinding tapered surfacesor in a vertical plane for effecting an axial feeding movement of a Workpiece for thru feed grinding operation. Said control wheel may beadjusted toward and away from the grinding wheel for work pieces ofvarious diameters. Said control wheel may also be moved axially eithermanually or by power. The means for effecting the above adjustmentsconsists of a member 45 pivotally and slidably mounted at 46 on bed I9for angular adjustment thereon. The pivot member 46 is set in preloadedball bearings 41 in order to provide a rigid mounting. Angularadjustment of member 45 is effected by means of screw 49 one end ofwhich is rotatably mounted in the bed I9, the other end of which isthreaded and inserted in a nut 49 in member 45. Integral with member 45is a cylinder 59 in which is slidably mounted a piston I having a pistonrod 52 one end of which is threaded. Said threaded end has a hollowhexagonal portion 64' into which a wrench may be inserted for rotatingsaid piston rod. Said threaded end 53' fits a nut 53 which is secured toa slide member 55. A lock nut 54 serves to lock slide 55 in adjustedposition relative to piston 5 I.

Membel- 45 has formed thereon two upwardly facing bearing surfaces, 56and 51, one V and one flat respectively. Member 55 has correspond ing Vand fiat surfaces 69 and 6| respectively for engaging surfaces 56 and 51on member 45.

Member 55 has a pair of upwardly facing guide surfaces extendingtransversely tn those on the underside thereof. One of these guides 65has a curved surface instead of the conventional V. The other guide 66has a nat surface. A member 61 having a curved surface 69 for matingwith guide 65 is secured to the underside of control wheel base 36 bymeans of screws 69.

The ilat guide 66 has slidably mounted thereon a rectangular block 15 inwhich is inserted a hardened button 16. A vertical adjusting screw 11threaded in a nut 19 in base 36 rests on said button. The upper end ofsaid screw extends thru the top of base 36 and has a hollow hexagonalportion 19 into which a wrench may be inserted for turning same. Asleeve 99 on said screw is graduated in terms of angles to which thecontrol wheel may be tilted. A clamp for said screw consists of asetscrew.9| having a beveled-point 92. One end or a pin 93 engages thesurface of screw shaft 11, the other end has a beveled point 94 incontact with point 92. By mounting motor 31 on control wheel base 36 anddriving wheel 35 thru resilient V belts the entire drive may be tiltedvas a unit with said base.

Feed mechanism-control wheel-The means for adjusting the control wheeltoward and from the grinding wheel consists of a feed screw 99 one endof which is threaded in a nut 9|. Said nut is mounted on a bracket 92which in turn is mounted on slide 55. The other end of said screw issupported in base 36 on spaced ball bearings 93 and 94. Between saidbearings a worm wheel 95 is mounted on said screw shaft. A worm gear 96on shaft 91 engages said worm wheel. A handwheel 98 on shaft 91 servesas a means for turning said shaft gears and screw for adjusting base 36and control wheel 35 toward and from the grinding wheel I5.

Work rest.-The work supporting device consists of a base member II9mounted directly on bed i9. Said base is slotted to receive a worksupporting bar III. Said bar has a work engaging surface inclined in thedirection of the control wheel. Work pieces are held in position justbefore and after the grinding operation in the case of thru feedgrinding by means of guides I I2 pivotally mounted on the base ||9 andurged toward the work by resilient means not shown.

-Dressing device for grinding wheel-The dressing device for the grindingwheel I5 consists of a bracket |99 attached to base II. A toolsupporting member I9| is slidably mounted on said bracket for areciprocating movement relative thereto. A diamond tool |92 is mountedon support member |93 which is adjustable vertically and horizontallyrelative to wheel I 5 by means of a knob |99 on a feed screw not shown.The reciprocating movement is effected by a piston |94 in cylinder |95and connected to member |9| by piston rOd |06.

Dressing device for control wheel.-The means for dressing the controlwheel consists of a diamond holder in the form of a block |29 mounted onthe rear of one of the guides |I2. Said block has a diamond tool |2|removably mounted therein in position to engage the surface of controlwheel 35.

Hydraulic features-The hydraulic system consists of two hydraulic motors59 and |95. Motor 59 provides the traverse movement oi' control wheelslide 55. Motor |95 receives fluid under pressure simultaneously withthe supply to motor 59.

Fluid under pressure is supplied by a pump |39 driven by motor |3|. Flowof fluid in said system is heldA uniform by pressure operated reliefvalve |32 in conjunction with throttle valve |33 as described incopending application Serial No. 390,432. filed April 25, 1941.

Said fluid under pressure passes from valve |33 thru line |35 andreversing valves |49 and I4I. Valve |49 directs fluid to one side or theother of cylinder 59 thru lines |51 and |59. The rate of flow thru saidvalve is controlled by a throttle valve |91 which is built into valve|49.

In the Same manner fluid under pressure is directed by valve I4I thruline |46 or line |41 to cylinder |95, the rate of flow being controlledby throttle valve |99. Valve |49 is normally locked in inoperativeposition by means of a latch |95 pivotally mounted on the knob of saidvalve and held in slot |69 by spring |61. The reason for sentially of aseriesgenerator |44 having series fields |50 and |5| and-a rheostat |52fo'.` varying the output ofsaid generator. Said'generator is connectedto a series type motor 31 having a series field |55 and a resistor |58which may be set for a predetermined motor speed, in this case a speedsuitable for dressing the control wheel and which is substantiallyhigher than the range of speeds used for grinding which are determinedby the rheostat |52.

The regenerative braking of motor 31 is accomplished in the followingmanner. An electric valve |53 is provided inthe motor generator circuitbetween generator |44 and generator series field |5|. This valve permitscurrent to flow only from left to right in the excitation circuit, thatis, from generator |44 to motor 31. As soon as grinding begins the workis caused to rotate by the action of the grinding wheel I5 and in turntends to drive the control wheel 35 and its motor 31 at a slightlyfaster rate than normal. In previous control wheel drives this tendencywould be checked before aiiecting said motor 31, usually by a gearedreduction unit. However, back lash in Such a unit would cause an abruptcheck in this increased speed which would have an undesirable affect onthe work being ground. In this invention, only a belt drive connectsmotor 31 with control wheel 35 and the increase in speed is transmitteddirectly to the motor. Said motor thus driven becomes a generator. Theload on the original generator being reduced, the flow of current thrufields |5| and |55 is also reduced and the normal tendency of the motoris to increase speed. However, rectifier 220 provides the necessaryadditional excitation for the field windings |5| and |55 to enable saidmotor to maintain the selected speed and to resist any tendency toincrease said speed. The current now generated by the motor will flowfrom motor 31 thru rectifier 220 back to generator |44 but said currentcannot flow back thru field windings |5| and |55 to decrease theexcitation. Preventing a decrease in motor excitation is essential toaid in the braking operation for motor 35. Regenerative braking is thusapplied to the control wheel drive and functions during the entiregrinding operation to provide a smooth running control wheel. Thiseffect is made possible because the variable voltage drive is capable ofcarrying substantially full load at speeds low enough that even with thelimited speed reduction ratio of belt drive the necessary control wheelSpeeds may be obtained.

Alternating current is suppliedto motors |3|. |40, |42 and |43 fromlines I, 2 and 3 thru suit able relays. Said relays are energized bycurrent at a lower voltage than that used on the motors. Said current issupplied from lines and 3 thru a transformer |60 to lines |6|and |62. Amaster start switch |33 and a, master stop switch |64 are inserted inline |6|. Line |82 is a return line.

A selector switch |10 may be set to determine which motors should be inoperation for each of the conditions of setting up, grinding, anddressing. The grinding wheel motor is controlled by a relay |15 actuatedby a coil |16. One contact |11 of said relay is connected to a normallyopen contact |18 in relay |19.A Said relay controls oil pump motor |3|and is actuated by coil |80. A normally closed contact |8| in relay |19includes the rheostat |52 in the variable voltage generator. Saidrheostat is set for driving control wheel 35 at a. predetermined speedfor grinding. .Contact |18 in relay |19 and contact |11 in relay |15when closed complete a circuit which includes resistor |56 in the fieldcircuit of control wheel motor 31. The purpose of this circuit is todrive said control wheel at a relatively high speed for dressing.

A third relay |85 having a coil |86 controls the generator driving motor|42 and coolant pump motor |43 which are connected in parallel. Lines|81 and |88 supply the primary oi transformer 2|0. The transformersecondary 2| supplies rectifier 220 in the variable voltage drivecircuit for control wheel 35.

` Operation In order to start the machine, the operator presses masterstart button |53. This energizes coil |90 of relay |9| to close saidrelay and direct current to selector switch |10. Said relay alsoestablishes a holding circuit for coil |90. With contact |1| of' saidselector switch closed, coil |80 would be energized thru line 200 toclose relay ber 45.

|19 and start the oil pump motor |3|.

The first operation is to set up the machine.

For this operation the only motor which might be needed would be the oilpump motor` |3|. By

4closing contact |1| of selector switch |10, current is directed thruline 200 to energize coil of relay |19 which closes the circuit to oilpump motor 3|. The control wheel 35 may then be adjusted toward thegrinding wheel I5 by turning rhand wheel 88 until said wheel is inposition for a Work piece of the desired size. This isv determined byadjusting wheel 35 until the work piece has moved up the inclinedsurface of bar s0 that the center of the work is in the desired positionrelative to the center of the wheel.

This position may be above or below the centers of wheels l5 and 35depending on the kind of work to be ground. Work supporting bar may beraised or lowered when necessary by any suitable adjusting means. Thedesired angle of skew may be obtained at this time by turning screw 11until said angle is indicated on graduated sleeve 80. If it is desiredto grind a tapered work piece, wheel 35 may be so ad-v justed by turningscrew 48 until the desired taper is indicated on a graduated plate 4| onmem- Grinding wheel i5 is then shifted forward by hand wheel 25 until itengages a gauge or master work piece at which point ring 3| is clampedto hand wheel 25 by means of clamping bolt 30 and the feed may beeffected by moving handle 23 which is mounted in said ring. The extentof movement of said handle in both directions is limited by positivestops.

It is desirable that the wheels |5 and 35 be properly dressed beforebeginning a grinding operation. For this operation,y the selector switch|10 is turned to the dress position. In this position contacts |12 and|13 are both closed. Contact 1| actuates relays |15 and |35 to operatewheel motor |40, and generator drive motor |42 and coolant pump motor|43. Contact |13 actuates relay |19 to start oil pump motor III.Operation of relay |19 opens the contact |0| to thus open the circuitthru rheostat |52 thus removing said rheostat from the circuit ofgenerator field Said rheostat controls the grinding speed of controlwheel 35. At the same time, contact |18 is closed inserting resistor |56in motor field circuit |55. Said resistor |55 is adjusted to cause saidmotor to run at a relatively high speed suitable for dressing.

Assuming that the wheel 35 has already been tilted to the desired angleof skew, a gauge or finished work piece, while resting on bar is rubbedagainst the stationary wheel 35 leaving a mark thereon. Said wheel isthen withdrawn as described above` to a position in line with diamond|2I. Said diamond is raised or lowered to the mark on the wheel andreversing valve |48 isshifted to direct fluid to the head end ofcylinder 50. The wheel is thus caused to traverse past the diamond |2|with said diamond following the path of travel of the work thereon.Valve |48 is reversed and iiuid directed to the rod end of cylinder 50to return wheel 35 to its original position.

If wheel 35 has been thrown out of alignment with grinding wheel |5 bythe skewing adjustment, this condition may be corrected by looseninglock nut 54 and turning shaft 52 in nut 53 by inserting a wrench in thehollow hexagonal head 54. By this means base 35 may be shifted to placewheel 35 in alignment with grinding wheel I5.

Diamond |02 is always in alignment with the surface of grinding wheeli5. This alignment is maintained of course by periodical adjustment ofknob |08. Traverse of the diamond |02 across wheel i5 is initiated byshifting valve |4| to direct fluid under pressure to the head end ofcylinder |05. Said diamond then makes a pass across the wheel l5 and isreturned to starting position by shifting valve |4| in the oppositedirection.

With the dressing and set up operations completed the operator is readyto begin a grinding operation. The selector switch is turned to theposition marked grind. In order to clarify the functions of the selectorswitch they may be listed as follows:

Set up-Oil pump motor only.

Dress-Oil pump, wheel and coolant motor and control Wheel.

Grind-Wheel and coolant motors only and control wheel.

Thus in the grinding position contactor |14 is closed to direct currentthru line |95 to actuate relay |15 for the grinding wheel motor |40 andthru line |91 to actuate relay |85 for coolant pump motor |43 andgenerator motor |42 to control wheel motor 31.

For thru feed work the grinding wheel is shifted forward to provide agrinding throat of the desired size, assuming of course that the controlwheel has been tilted to the desired angle and the work supporting baradjusted to the desired height. A work piece i2 may be inserted manuallyin the grinding throat or may be fed thereto by any suitable loadingdevice. Said work is caused to move axially by 8 the control wheel 35while being ground by the grinding wheel |5.

For plunge cut grinding the work is placed in the grinding throat eithermanually or by some sort of loading device. The grinding wheel Il ismoved forward by means of lever 20 or by some suitable power means. Theforward movement of said grinding wheel continues to a predeterminedposition determined by the limit of movement of handle 25 at which pointthe work should be ground to size. The grinding wheel Il is then backedoil' and the work |2 removed from the grinding throat.

We claim:

1. A center-less grinding machine comprising e grinding wheel and acontrol wheel, a support for said control wheel, a pair of guidesurfaces on said support for movement thereof toward and from saidgrinding wheel, means for effecting said movement, one of said guidesurfaces being curved about an axis parallel with said direction ofmovement and means for tilting said control wheel support on said curvedsurface away from a vertical position. r

2. A grinding machine having a bed, a wheel support thereon movabletoward and from s work piece, said support having two guide members, onehaving a flat surface, the other having a surface curved transversely ofthe direction of movement of said support, said nrst member consistingof a separate slide and an adjustable connection between said slide andsaid support.

3. A grinding machine having a bed, a grinding wheel and a control wheelhaving opposed peripheral faces, one of said wheels being movable towardthe other for a grinding feed, a work rest for supporting a work piecein operative relation to said peripheral faces, a dressing tool mountedon said work rest and means for eifecting a traversing movement of saidcontrol wheel past said tool.

4. A grinding machine having a bed, s grinding wheel and a control wheelhaving opposed peripheral faces, one of said wheels being movable towardthe other for a grinding feed, a work reet for supporting a work piecein operative relation to said peripheral faces, a dressing tool mountedon said work rest, means for effecting a relative traversing movementbetween said control wheel and said tool and means to prevent saidtraversing movement when said wheel is in forward or grinding position.

5. A grinding machine having a bed, a grinding wheel and a control wheelhaving opposed peripheral faces, one of said wheels being movable towardthe other for a grinding feed, work guides for directing a work pieceinto operative relation to said peripheral faces, a dressing toolmounted on one of said guides and means for effecting s traversingmovement of said control wheel past said dressing tool.

6. A grinding machine having a bed, a grinding wheel and a control wheelhaving opposed peripheral faces, one of said wheels being movable towardthe other for a grinding feed, a work rest for supporting a work piecein operative relation to said peripheral faces, a dressing tool mountedin a fixed position on said machine in the same plane as the axis of thework, means for tilting said control wheel so that it causes the work tomove axially across the face of the grinding wheel, and means foreffecting a traversing movement of said control wheel past said dressingtool whereby to dress said wheel along the/path of travel of the work. f

'7. A grinding machine having opposed grinding and control wheels,ysupports for said wheels, means for mounting one of said supports formovement toward and from the other, means for effecting angularadjustment of one of said supports in both a vertical and horizontalplane, said support being slidably mo-unted for a traversing movement, adressing tool and ymeans for effecting said movement past said dressingtool in any position of angular adjustment.

8. A grinding machine comprising a bed, a swivel table mounted thereon,for angular adjustment relative thereto, a carriage slidably mounted onsaid table for a traversing movement thereon a wheel base slidablymounted on said carriage for movement transversely relative thereto,spaced guide surfaces on said wheel base, mating f guide surfaces onsaid carriage, one of said guides being cylindrical in shape and meansfor tilting said base on said cylindrical guides.A

9. A grinding machine having opposed grinding and control wheels,supports for said wheels,

. means actuated by fluid under pressure for effecting a traversingmovement of one of said wheels and means for adjusting said wheel in anaxial direction relative to saidother wheel.

10. A grinding machine comprising a bed, a grinding wheel support,4 agrinding wheel rotatably mounted thereon, a second wheel support, acontrol wheel rotatably mounted thereon and peripherally opposed to saidgrinding wheel, said control wheel base having two guide surfaces formovement toward and from the grinding wheel, one of which is curvedabout/an axis extending transversely of the control wheel axis formovement toward and from the grinding wheel, means for tilting saidsupport on said curved guide surface and means for effecting relativeaxial movement between said wheels to bring them into proper alignmentafter tilting.

l1. A grinding machine having a bed, a grinding wheel and a controlwheel having opposed peripheral faces, one of said wheels being movabletoward the other for a grinding feed, a work rest for supporting a. workpiece in operative relation to said peripheral faces, a dressing tool,

lmeans for effecting a relativer traversingmover ment between said tool.and onez'oi ysaid wheels, means for driving said wheel at a speedsuitable for grinding and also at a speed suitable for dressing, and acommon control means for said wheel speed and said traversing means.

l2. A grinding machine having a bed, a grinding wheel and a controlwheel having opposed peripheral faces, one of said wheels being movabletoward the other for a grinding feed, a work rest for supporting a workpiece in operative relation to said peripheral faces, a dressing tool,means for effecting a relative traversing movement between said tool andan abrasive wheel including a hydraulic motor, a pump for supplying uidunder pressure to said motor, means for driving said wheel at speedssuitable for grinding and also at a speed suitable for dressing and acommon control means for said wheel speed and said fluid under pressure.

13. A grinding machine comprising a bed, a grinding wheel and a controlwheel rotatably mounted thereon, a work rest between said wheels.

means for effecting axial, transverse and angular adjustment of one ofsaid wheels relative to the other, hydraulic means for effecting one ofying the speed of one of said motors for dressing 10 or grinding andmeans for selectively controlling said motors for each of the conditionsof set up, dress and grind.

14. A grinding machine comprising a bed, a

swivel table mounted thereon, for angular adjustrnent relative thereto,a carriage slidably mounted on said table for a traversing movementthereon a wheel base slidably mounted on saidr carriage for movementtransversely relative thereto, spaced guide surfaces on said wheel base,mating guide surfaces on said carriage, one of said guides beingcylindrical in shape and means for tilting said base on said cylindricalguides, means for driving said wheel including a motor, driving beltsconnecting said motor and said wheel, said motor being mounted on saidwheel base and tiltable therewith.

15. A grinding machine comprising a bed. a Wheel base slidably mountedon said bed, an abrasive wheel rotatably mounted on said'base, saidwheel base having spaced supporting surfaces, one disposed substantiallybeneath said wheel and being curved transversely of the direction ofmovement of said base, the other. at'the opposite side of said base andcomprising a slidable member separate from said base and means forraising and lowering one end of said base relative to said secondsupport member,

16. A grinding machine comprising a supporting member, a wheel base, anabrasive wheel rotatably mounted on said base, means disposedsubstantially beneath the abrasive wheel for supporting said wheel baseon said supporting member so that the wheel base may be tilted in aplane substantially parallel with the axis of the abrasive wheel, andsupporting devices located at'one side of said supporting means forsupporting said wheel base on said support member, said supportingdevices including an adjustable means whereby said wheel base may bepositively tilted to different set angular positions.

17. vA grinding machine comprising a supporting member, a' wheel base,an abrasive wheel rotatably mounted on said base, means disposedsubstantially beneath the abrasive wheel for supporting said wheel baseon said supporting memxber so that the wheel base may be tilted in aabrasive wheel, and supporting devices located at one side of saidsupporting means for supporting said wheel base on said support member,said devices including a curved portion on said base and a flat memberindependent of said base and spaced from said curved portion.

18. A grinding machine having abed, a grinding wheel and a control wheelhaving opposed peripheral faces, one of said wheels being movable towardthe other for a grinding feed, a work rest for supporting a work piecein operative relation to ksaid peripheral faces, a dressing tool,hydraulic means for effecting a relative traversing movement betweensaid tool and one of said wheels including a motor driven pump, meansincluding a motor for driving said wheel at a speed suitable forgrinding and also at a speed suitable for dressing, and common controlmeans for said motors for changing said wheel speed when said traversingmovement is initiated.

19. A centerless grinding machine comprising a bed, wheel supportsmounted on said bed, a grinding wheel rotatably mounted on one oi.' saidsupports, a control wheel mounted on the other of said supports, meansfor driving said control wheel including a variable voltage drivemechanism consisting of a motor and generator in a loop circuit, saidcontrol wheel and motor being Y `,subject to an overhauling load, saidloop circuit including a generator series field winding which inresponse to said overhauling load would normally reduce the motor fieldstrength and cause increased motor speed, and a separate source ofcurrent for supplementing the output of the generator for energizingsaid fields whereby to cause said motor to maintain a uniform controlwheel speed and to resist an increase in said speed.

20. A centerless grinding machine comprising a bed, wheel supportsmounted on said bed, a grinding wheel rotatably mounted on one of saidsupports, a control wheel mounted on the other of said supports, meansfor driving said control wheel including a variable voltage drivemechanism consisting of a motor and generator in a loop circuit, saidcontrol wheel and motor being subject to an overhauling load, said loopcircuit including a generator series field winding which in response tcsaid overhauling load would normally reduce the motor eld strength andcause increased motor speed, said overhauling load causing said motor tofunction as a generator, a device for preventing passage thru said neldsof a current in the direction of that generated by said motor and thusto counteract the effect of said overhauling load on said control wheel.

21. A grinding machine having opposed grinding and control wheels,supports for said wheels, means for mounting one of said supports formovement toward and from the other, means for effecting angularadjustment of one of said sup- 12 ports in a horizontal plane, saidsupport being slidably mounted for a traversing movement, s dressingtool and means for effecting said traversing movement past said dressingtool in any position of angular adjustment while maintaining a fixedangular relation between the wheel axis and the direction of traverse.

HAROLD E. BAIBIGER.. JOHN A BOLLER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,184,011 Flanders Dec. i9. 19391,882,814 Haas Oct. 18, 1932 1,887,154 Guild et al. Nov. 8. 19821,483,748 Sanford Feb. 12, 1924 1,733,087 Heim Oct. 22, 1929 1,733,090Holmes Oct. 22, 1929 1,733,092 Einstein Oct. 22, 1929 1,842,375 EinsteinJan. 28, 1932 1,892,453 Fuller Dec. 27, 1932 1,938,757 Einstein et al.Dec. 12, 1933 1,978,279 Ogilvie Oct. 23, 1934 2,210,137 Bergstrom Aug.6, 1940 FOREIGN PA'I'ENTB Number Country Date 526,998 German June 12,1931 549,128 German Apr. 23, 1982 851,895 German Oct. 21, 1937

